Cyclic GMP kinase and RhoA Ser188 phosphorylation integrate pro- and antifibrotic signals in blood vessels

Mol Cell Biol. 2009 Nov;29(22):6018-32. doi: 10.1128/MCB.00225-09. Epub 2009 Sep 8.


Vascular fibrosis is a major complication of hypertension and atherosclerosis, yet it is largely untreatable. Natriuretic peptides (NPs) repress fibrogenic activation of vascular smooth muscle cells (VSMCs), but the intracellular mechanism mediating this effect remains undetermined. Here we show that inhibition of RhoA through phosphorylation at Ser188, the site targeted by the NP effector cyclic GMP (cGMP)-dependent protein kinase I (cGK I), is critical to fully exert antifibrotic potential. cGK I(+/-) mouse blood vessels exhibited an attenuated P-RhoA level and concurrently increased RhoA/ROCK signaling. Importantly, cGK I insufficiency caused dynamic recruitment of ROCK into the fibrogenic programs, thereby eliciting exaggerated vascular hypertrophy and fibrosis. Transgenic expression of cGK I-unphosphorylatable RhoA(A188) in VSMCs augmented ROCK activity, vascular hypertrophy, and fibrosis more prominently than did that of wild-type RhoA, consistent with the notion that RhoA(A188) escapes the intrinsic inhibition by cGK I. Additionally, VSMCs expressing RhoA(A188) became refractory to the antifibrotic effects of NPs. Our results identify cGK I-mediated Ser188 phosphorylation of RhoA as a converging node for pro- and antifibrotic signals and may explain how diminished cGMP signaling, commonly associated with vascular malfunction, predisposes individuals to vascular fibrosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin II / pharmacology
  • Animals
  • Blood Vessels / drug effects
  • Blood Vessels / enzymology*
  • Blood Vessels / pathology*
  • Cyclic GMP / pharmacology
  • Cyclic GMP-Dependent Protein Kinases / deficiency
  • Cyclic GMP-Dependent Protein Kinases / metabolism*
  • Enzyme Activation / drug effects
  • Fibrosis
  • Gene Expression Regulation / drug effects
  • Humans
  • Hypertrophy
  • Mice
  • Mice, Transgenic
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / enzymology
  • Muscle, Smooth, Vascular / pathology
  • Mutant Proteins / metabolism
  • Organ Specificity / drug effects
  • Phosphorylation / drug effects
  • Phosphoserine / metabolism*
  • Protein Biosynthesis / drug effects
  • Serum Response Element / genetics
  • Signal Transduction* / drug effects
  • Transcription, Genetic / drug effects
  • rho-Associated Kinases / metabolism*
  • rhoA GTP-Binding Protein / metabolism*


  • Mutant Proteins
  • Angiotensin II
  • Phosphoserine
  • rho-Associated Kinases
  • Cyclic GMP-Dependent Protein Kinases
  • rhoA GTP-Binding Protein
  • Cyclic GMP